Plunger packing



Feb. 10, 1942.

R. A. YOHPE PLUNGER PACKING Filed June 30, 1941 A TTORNEYS.

Patented Feb. 10, 1942 TATS PATT FFICE 2,272,862 PLUNGER PACKINGReinhard A. Yohpe, Battle Creek, Mich., assignor to Union Steam PumpCompany, Battle Creek,

Mich.

3 Claims.

This invention relates to improvements in plunger packings.

The main objects of this invention are:

First, to provide an annular, liquid tight packing for a reciprocatingplunger such as is employed in homogenizing apparatuses.

Second, to provide a packing of the type described preventing theleakage of liquid axially of the plunger, in which the packing materialis restrained in a particular manner in engagement with a reciprocableplunger so as to increase the effectiveness of the sealing action aswell as the life of the packing.

Third, to provide a packing of the type described wherein eifectivenessof the sealing of the plunger is dependent primarily upon thecharacteristics of the packing itself rather than upon the hydraulicaction thereon of the liquid which it is desired to confine.

Further objects relating to details and economies of my invention willappear from the description to follow. The invention is defined in theclaims.

A structure embodying the features of my invention is illustrated in theaccompanying drawing, wherein:

Fig. 1 is a fragmentary view in side elevation partially broken away andin vertical section illustrating the pumping chamber of a homogenizingmachine employed for homogenizing fatty emulsions such as milk,including the pumping plunger with the sealing arrangement of myinvention in operative association therewith.

Fig. 2 is a perspective view illustrating th special stuffing boxemployed in the seal of my invention.

Fig. 3 is a perspective view illustrating the special packing designedfor coaction with the stuffing box of Fig. 2.

Fig. 4 is a perspective view illustrating the special sealing capserving the function of a compressor head and gland in association withthe stufiing box and packing of Figs. 2 and 3.

This invention relates to a packing or liquid seal for the plunger of ahomogenizing machine such as is commonly employed. in th homogenizationof fatty emulsions by breaking up the fatty particles thereof. Thesemachines operate at high pressure and it is necessary to provide someeffective means for preventing leakage of the fatty liquid axially ofthe pump or plunger at the pumping state of the process. Moreparticularly, the invention relates to a packing or sealing arrangementfor the foregoing purposes which is characterized by the effectivenessof the seal provided thereby which, in this case, functions inaccordance with a different principle than has been heretofore employedin machines of this type and by the fact that the life of the packing isgreatly increased.

Referring to the drawing, the reference numeral I in general designatesthe pump head of a homogenizing apparatus including a casting 2 definingan elongated, cylindrical, pumping chamber 3 which is closed at one endby a heavy closure plate or head 30 bolted thereto, a suitable sealinggasket 4 beinginterposed.

The liquid or fatty emulsion, such as milk, is introduced into chamber 3through an inlet valve 5 coacting with a valve seat 6 at the lowerdiametral side of the chamber and is discharged therefrom past adischarge valv I coacting with a seat 8 which communicates with thecylindrical chamber 3 on the opposite or upper diametral side thereof.

The pumping operation is performed by an elongated, cylindrical plunger9 which is reciprocated in the cylinder or chamber by any suitableactuating means coupled to the plunger externally Of the pumping chamberat 3..

The sealing assembly of my invention includes a stufiing box member I lin the form of an elongated, annular, sleeve-like member having ashoulder ll telescoped into a counterbore I2 of the cylindrical chamber3 with a sealing gasket 13 interposed. Member I! is concentric of theplunger and has an end extension 14 of reduced diameter projectinginternally of the cylinder at least as far as the inlet and dischargevalves 5, l and the inlet valve is provided with a radially projectingtappet or lug l5 which engages extension I4 when the inlet valve iselevated, thereby limiting the throw of the valve and at the same timepreventing the same from striking the plunger at the end of said throw.Valves 5, 1 are provided with integral, cross-shaped guide arms isguiding the same in their radial seating and unseating movements.

Externally of the pump chamber housing, the stuffing box member H isprovided with an annular surface I! of V-shaped outline, the apex of theV pointing outwardly of the pumping cylinder or chamber, and coactingwith this surface I provide the resilient leather compressible packingI6 which is held against the surface I! by a cap l9 acting as a closureand pressure head. Bolts 20 extending through the opposite closure capsor heads 3, i9 serve to maintain the parts axially compressed forpurposes to be described. It will be noted by reference to Figs. 1, 3and 4, that the resilient leather packing I8 is of annular outlinesurrounding the plunger and is formed in a V-shaped or cupped sectioncomplemental to the outline of the stuffing box surface H, the innerplunger engaging portion of the packing being inclined in the axialdirection of the plunger; likewise that the pressure head I9 is providedon its inner sid with an annular groove adjacent its radial innerperiphery, the said groove having a V-shaped surface 2| at its bottomcorresponding to the V-shaped outline of surface I! and the packing l8.

In operation, sufficient force is applied on the pressure head 9 tosubstantially compress the resilient packing l8 and urge the innerannular extremity thereof into sealing engagement with the plunger, thelatter being constrained at either axial side thereof by the V-shapedsurfaces of the end of the stuffing box and the pressure head with whichit is nestingly engaged. In this manner, the angularity of the packingsection cannot b changed by hydraulic action axially of the plunger, theonly hydraulic action tending to increase the effectiveness ofengagement with the plunger existing at the very point of engagement ofthe packing with the plunger. I depend, however, primarily on theplasticity or resiliency of th material of the highly compressed packingto cause the material thereof to urge itself radially inwardly againstthe plunger.

I am aware that in apparatuses of this type it has been proposed toemploy a packing disposed inside the bore of the plunger stuffing box onth side thereof toward the pumping chamber, depending upon the hydraulicpressure to urge the packing against the plunger. However, I have foundthat the hydraulic pressure has a definite tendency to change theangularity of the packing and in time decrease the efiectiveness of itssealing action. In such cases, reliance is placed on the packingspreading out to compensate for wear; however, in the presentconstruction, compensation for wear is effected solely by the radialinward flow or creep of the material under compression. This is anentirely different and much more effective action and the structure ischaracterized by a longer effective life. Only the tip of the packing atits radial innermost periphery is in contact with the liquid on theplunger. Consequently, it is not subject to being coated and impregnatedwith the fatty sugar-bearing content of the latter. This I regard as afeature of substantial importance in the present invention as well asthe fact that the angles of the packing l8 cannot be changed with age toalter the effectiveness of their plunger engagement. Being axiallyconstrained on both sides, the angle of my V-shaped packing cannot bechanged. It will likewis be noted that the compression head 3 andcompression gland l9 on the cylinder block 2 are held in place by thesame set of bolts extending through the cylinder block itself. This is ahighly advantageous arrangement by reason of its simplicity and the easeand speed of installing which the same make possible.

An important feature of the invention is the fact that only an extremelysmall area of the packing is exposed to the liquid being pumpedresulting in a very sanitary condition when pumping milk or other foodproducts. The greater the area of the packing exposed to the liquid, thegreater will be the bacterial action on the liquid and with the packingsuch as proposed this bacterial action is at a minimum. With ordinarytypes of packing located inside the stufiing box, a much larger area isexposed to the liquid. Also the proposed arrangement reduces theabsorption of liquid by the packing to a minimum because the packing ishighly compressed tending to force out liquid which normally would beabsorbed by capillary action, and this is a further sanitary feature.

The terms and expressions which have been herein employed are used asterms of description and not of limitation, and there is no intention,in the use of such terms and expressions, of excluding any equivalentsof the features shown and described. It is recognized that variousmodifications are possible within the scope of the invention claimed.

Having thus described my invention, what I claim as new and desire tosecure by Letters Patent is:

1, In a structure of the type described having a housing providing apump chamber and having a plunger reciprocable axially thereof, aliquid-tight annular seal surrounding said plunger comprising asleeve-like stuffing box telescoped with said plunger and extending intosaid chamber, said stuffing box having an outwardly convexed V-shapedsurface concentric with the plunger on the outside of said housing andchamber, a cap externally telescoping said stuffing box at the outer endof the latter and provided with an annular V-shaped recess complementalin shape to said stulhng box surface, an annular resilient packinghaving a V-shaped cross section in nested relation to said surface, andmeans for drawing said cap axially toward said stuffing box to compresssaid packing and urge the inner peripheral surface thereof radiallyinwardly for sealing engagement with the plunger, the resilience of thecompressed packing maintaining the same against said plunger followingwear on the packing.

2. In a structure of the type described having a housing providing apump chamber and having a plunger reciprocable axially thereof, aliquidtight annular seal surrounding said plunger comprising asleevelike stuffing box telescoped with said plunger and extending intosaid chamher, said stuffing box having an outwardly convexed surfaceconcentric with the plunger, a cap externally telescoping said stuffingbox at the outer end of the latter and provided with an annular recesscomplemental in shape to said stuffing box surface, an annular resilientpacking having a cupped cross section in nested relation to saidsurface, and means for drawing said cap axially toward said stuffing boxto compress said packing and urge the inner peripheral surface thereofradially inwardly for sealing engagement with the plunger, theresilience of the compressed packing maintaining the same against saidplunger following wear on the packing, and a sealing member between saidstuffing box and said chamber to prevent passage of fluid between saidstufiing box and chamber to said packing.

3. In a packing structure for a plunger and pump chamber of the typdescribed, a stuffing box concentric with and fitting around the plungerand provided with an outwardly angled V-shaped annular surfacesurrounding and concentric with the plunger, a closure cap provided withan internal annular V-shaped surface complemental to said first-namedsurface and likewise concentric with and fitted around said plunger,means for pressing said cap to position toward said stuffing box tocompress a packing between said surfaces, and an annular resilientpacking of V-section complementing said surfaces and disposed nestinglythcrebetween under substantial compression with the inner periphery ofthe packing in sealing engagement with said plunger.

REINHARD A. YOHPE.

